Profiles previously had no validation, so config errors surfaced far
from their origin and cryptically:
- explicit profile missing `model` fell back to the profile NAME as the
model (a profile named "local" would send "model": "local")
- default profile missing `model` with no model param produced
"model": null -> API 400
- missing `api_url` surfaced as requests InvalidURL
_resolve_model_profile now runs _validate_profile (dict type + api_url)
before reading fields and _require_model on the effective model,
raising ValueErrors that name the profile, the missing field, and the
config.json path to fix. Bare model names still legally substitute for
a default profile's missing model field.
Tests: new TestH2SchemaValidation (6 cases: missing model/api_url,
null-model via default profile, bare-name substitution, non-dict
profile, e2e create_llm_client); full suite 282 passed.
~/.cert/deepseek.key is a DeepSeek-only credential; when a models profile
specified its own api_key_env (e.g. MOONSHOT_API_KEY) but the env var was
unset, resolve_api_key silently read that file and sent the DeepSeek key
as Bearer to a third-party endpoint (cross-vendor credential leak).
resolve_api_key gains allow_key_file (default True for the legacy flat
api section); create_llm_client passes allow_key_file=profile is None so
any profile path raises a clear RuntimeError instead, pointing users to
set the env var or use "" for local keyless endpoints.
Tests: new TestH1KeyIsolation (4 cases) with a mocked readable
deepseek.key proving the profile path errors out while the flat api
section still reads the file; full suite 276 passed.